The present invention relates to network management apparatuses and methods of selecting a base station for software update. In particular, the present invention relates to a network management apparatus and a method of selecting a base station for software update for carrying out software update in a wireless communication system base station.
In typical conventional communication networks, it is important to ensure reliability to prevent interruption of communication. For this reason, software for providing communication services and controlling the operation of communication networks should be preferably updated without having to stop communication services. For example, a method of updating software in a system in which hardware is redundantly configured so that software installed in non-operating hardware is updated is disclosed in Japanese Unexamined Patent Application Publication No. Hei-7-319683 and No. 2001-56759.
On the other hand, wireless communication networks allow each base station to communicate with each wireless terminal within an area called a “cell”, which is a coverage area of radio waves from the base station. Typical cells have a radius of several kilometers. Thus, typical wireless communication networks are characterized in that they can accommodate only a smaller number of users with a smaller coverage area, compared with known wired communication networks (exchange networks). To overcome this disadvantage, in a typical wireless communication network, a large number of such base stations need to be arranged to provide communication services over a wide area. For this reason, if such many base stations are redundantly configured in the same manner as the wired communication network facility described in the Japanese Unexamined Patent Application Publication No. Hei-7-319683 and No. 2001-56759, the economical efficiency of communication networks is significantly impaired. In addition, in that case, a plurality of frequency bands and CDMA spread codes need to be assigned, which leads to waste of limited resources and decreases the number of users resulting in declining the capability of providing users with services. As a solution to this drawback, a method of updating software installed in a base station while communication services of the base station are suspended during a certain time period, such as midnight, is disclosed in Japanese Unexamined Patent Application Publication No. Hei-10-63498.
Furthermore, in CDMA wireless communication networks, a technique for updating software while uninterruptedly switching a communication path from the current wireless base station to another wireless base station or to a sector through the use of soft handover technology and electrical power control technology is described in Japanese Unexamined Patent Application Publication No. 2005-10821.